Background: We now know that children's language learning is strongly influenced by their linguistic environment including the type and quality of the language they hear. We also know that larger vocabularies during early childhood are associated with positive academic, economic, and even health outcomes later in life. Lacking, however, is a mechanistic understanding of the nature of the causal links between children's word learning and long-term outcomes. The current research addresses this gap by examining whether learning certain ?seed words??words with high inductive potential?accelerates word learning to a greater degree than other words and causes higher performance in non-linguistic categorization tasks. Specific Aim 1: To identify ?seed? words that are associated with consistently faster vocabulary growth Specific Aim 2: To determine whether teaching ?seed? words yields positive language outcomes. Specific Aim 3: To test when teaching seed words promotes category induction in nonverbal tasks. Methodology: We will examine children's language and cognitive development in a microgenetic longitudinal study. One-hundred twenty 30- to 36-month-old children will be randomly assigned to one of three experimental conditions: (a) a high inductive word training condition, (b) a low inductive potential word training condition, and (c) a control condition in which children do not receive language training. We predict that children trained on previously identified ?seed words? will have faster vocabulary development and higher performance on a nonverbal category induction task than children in the other two experimental conditions. Significance: The proposed studies will contribute to a greater understanding of children's language development. By undertaking a theory-guided identification of early-learned ?seed? words and measuring the effect that learning these words has on subsequent language development, the proposed work will inform the design of future language interventions. By investigating the relationship between word knowledge and category learning, the proposed work aims to understand why language abilities are so closely linked to other cognitive abilities.